Shock-absorbing handle structure for pneumatic tools



May 16, 1961 2,984,210

SHOCK-ABSORBING HANDLE STRUCTURE FOR PNEUMATIC TOOLS G. H. FUEHRER Filed July 15, 1958 lnl'lI' INVENTOR.

$50265 A FUEHQEA This invention relates to pneumatically-actuated tools and more particularly to an improved handle structure for use on such tools featuring rigid handgrips in combination with resilient shock-absorbing inserets in the areas thereof to which pressure is commonly applied by the operator in the use of the tool.

Pneumatically-actuated tools have been made in a great variety of forms for various uses in which a reciprocal impact element supplies the power to the working element of the tool. Among the vexatious shortcomings of such tools as heretofore provided are the severe vibratory shock stresses imparted to the operator through the handle required to hold and guide the tool against the material being worked. Numerous handle designs have been proposed heretofore in an attempt to minimize the disagreeable and tiring elforts of shock and vibration but such attempts have been only partially successful. Among the proposals made but found lacking in effectiveness is that of providing the grip portions of the handle structure with resilient tubular handgrips. These are subject to many defects and objections. For example, pneumatic tools are heavy and exposed to rough handling causing the handgrips to be distorted, stretched, damaged and detached from the handle proper. Further, it is found that the handgrips are easily punctured, torn or otherwise damaged. Also, the lubricant used on the working parts of the tool is easily absorbed by the resilient handgrips rendering them slippery and difficult to hold, thereby creating a serious hazard to the workman.

These and numerous other shortcomings of prior attempts to provide a shock-absorbing handgrip are obviated by the present invention making use of handgrips formed in part of rigid materials and in part of resilient, shock-absorbent materials restricted to those portions of the handgrip to which the operator applies pressure in the normal usage of the tool.

Those portions of the handgrip most likely to be contacted by other objects in the handling and transportation of the tool are preferably formed of rigid metallic materials. Other major portions of the rigid metallic handgrip are cut away to seat hollow inserts of resilient material with thei exposed surfaces merging smoothly with the adjacent exposed portions of the rigid handle structure. Normal lifting and handling of the pneumatic tool is performed by forces applied directly to the rigid metallic portions of the handle whereas the operator-applied forces used to press the tool against the material being worked are applied through the shock absorbing resilient inserts thereby greatly increasing the comfort of the operator without in anywise sacrificing safety or overall ruggedness in the design of the tool.

Accordingly, it is a primary object of the present invention to provide an improved handle structure for use with pneumatically-actuated tools.

Another object of the invention is the provision of an improved handle structure for percussive tools featuring a handgrip formed in major part of rigid materials and having shock-absorbing resilient inserts for those portions to which the operator applies pressure in the normal use of the tool.

Another object of the invention is the provision of a.

2,984,210 Patented May 16, 1961 rugged shock-absorbing handgrip for use on pneumatic tools having an elongated hollow insert of resilient material removably held in place against one side of the handgrip.

These and other more specific objects will appear upon reading the following specification and claims and upon considering in connection therewith the attached drawing to which they relate.

Referring now to the drawing in which a preferred embodiment of the invention is illustrated:

Figure 1 is a side elevational view of a typical pneumatic tool provided with a handle structure incorporating the present invention;

Figure 2 is a transverse sectional view on an enlarged scale taken through the handle section longitudinally of the tool; and

Figure 3 is a transverse sectional view on an enlarged scale taken along line 33 on Figure 2.

Referring to Figure 1 there is shown a typical pneumatically-actuated tool, designated generally 10, of the socalled pavement breaker type having a generally tubular main body 11. It will be understood that main body '11 houses a reciprocal piston adapted to be reciprocated rapidly longitudinally thereof by pressurized air delivered to the opposite ends of the piston by a suitable reversible valving mechanism as, for example, that disclosed in Gillerstrom Patent 2,613,646, granted October 14, 1952. The pressurized air for the operation of the tool is supplied through a hose connectable to the tool as through inlet coupling 12. Resiliently connected to the lower end of main body 11 is a chucking device 13 adapted to support reciprocably any suitable working tool such'as the chisel, the upper end only of which is indicated at 14. If further details of the working parts of the tool are desired, reference may be had to my co-pending application for United States Letters Patent Serial No. 726,454, filed April 4, 1958, for Pavement Breaker, now abancloned.

The combined backhead and handle structure, desig nated generally 20, incorporating the improvements of the present invention is secured to the upper end of main body 11 as by a pair of bolts 21 located on the opposite sides of the handle structure. As here shown, the handle structure proper comprises an elongated member extending transversely of the tool backhead 24 and includes a pair of handgrips 23, 23 projecting in opposite direc a unitary insert 30 formed of suitable elastorneric material resistant to attack by lubricants. A particularly suitable material for this purpose comprises neoprene compounded to a Shore softness in the vicinity of 30. Each of the inserts has the general cross-section configuration made clear by Figures 2 and 3, the opposite lateral surfaces 31, 31 merging smoothly with the adjacent surfaces 32, 32 of the metal portions of handgrip 23. The intervening surfaces 33 are complemental to the opposed surfaces of handgrips 23 so as to seat firmly thereagainst in the assembled position of the inserts.

The means for holding inserts 30, 30 securely anchored in the cut-away portions of the handgrips 23 will be best understood by reference to Figure 2. The opposite ends of the inserts are desirably formed with annular extensions 35, 35 for close fitting assembly in the adjacent annular wells of the handle structure. Assembly of the inserts into these wells is accomplished by inserting first one endportion 35 and then bowing the midportion of the insert outwardly sufliciently to permit the assembly of the other end 35 into its seating well. Thereafter, the outer end of bore- 38' is filled with a closure disc 39 which may be securely anchored in place as by welding, brazing or the like 40.

Each of the discs 39 is provided with a threaded bore 41 offset from the center of the disc for receiving an assembly pin- 42 extending the full length of the insert with its forward end seating in a well 43" of the backhead structure. It will be understood that pin 42- lies flush against the lower inner wall of a generally tubular cavity 44 extending from end to end of the insert. The outer end of pin 42 is threaded to have a close frictional fit with the threads of bore 41. It will be clear from the foregoing that the anchor pin is highly effective in holding the lower inner portion of the insert firmly and rigidly seated in the complementarily shaped channel formed lengthwise of handgrips 23 while leaving the entire upper portion of the hollow insert free of obstruction and fully available to absorb vibration and shock loads incident to the operation of tool Pivotally mounted within an elongated channel 45 centrally of the handle structure is a control lever 46 for an air valve controlling the flow of compressed air to the reversible valving mechanism. It will be understood that normally handle 46 is held outwardly in the position shown wherein the air valve is closed. When depressed toward the underlying handgrip, control lever 46 is effective to depress stem 48 of the air control valve opening this valve in a manner well known to those familiar with this art.

In the use of the described tool it will be understood that the operator normally grasps the tool with one hand surrounding each of the handgrips 23 with the heel of the palm overlying the top of inserts 3t}, 30. Owing to the location of the rigid metallic portions 23 of the handgrip on the underside of the handles, all lifting and handling forces normally applied to the tool are applied directly to the rigid metal surfaces of these handgrips.

Once the tool is in place with the cutting end of chisel 14 bearing against the surface of the material being worked, the operator will depress the air valve handle 46 toward the resilient insert 30 thereby opening air valve 48. This will cause the piston Within main body 11 to reciprocate and to deliver high impact forces to cutting tool 14. The operator then applies pressure downwardly on handgrips forcing the cutting tool into the material. The pressure thus applied to inserts 30 through the heel of the hand deforms the resilient inserts downwardly toward locking pins 42. Under these conditions the resilient inserts are highly effective in aborsbing vibrations and shocks characteristic of the operation of the tool thereby isolating the operator from a major portion of the shock vibrations which would otherwise be transmitted to him. It will be understood that both hands are protected from shock in this manner even though the heel of one hand bears against the top of control lever 46. This is for the reason that when open, this lever will be pressed downwardly against and cushioned by the underlying insert, the latter acting in the same manner as the other insert to absorb vibrations of the tool.

It will be appreciated that it is impossible for the described inserts to become dislodged from their assembled positions. If, for any reason, they should become damaged or should lose their resiliency due to long service, it is a simple matter to replace the unserviceable insert with a replacement by unscrewing locking pins 42.

While the particular shock-absorbing handle structure for pneumatic tools herein shown and disclosed in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or de' sign herein shown other than as defined in the appended claims.

I claim:

1. In a pneumatically-operated tool of the type having a self-contained pneumatically-actuated reciprocable power unit extending lengthwise thereof and adapted to be manually supported against a work surface, that improvement which comprises a pair of metallic handgrips projecting laterally from one end portion of said tool each cut away lengthwise of. its upper midsection and having a full-bodied non-cut away lower exterior surface, a hollow tubular insert of resilient shock absorbing material substantially co-extensive with the cut away portion of each of said handgrips. and with the opposite ends of said tubular inserts interlocked with juxtaposed portions of said handgrip-s and cooperating therewith in forming a composite metallic and non-metallic handgrip having smoothly merging adjacent exterior surfaces.

2. The improvement defined in claim 1 characterized in the provision of removable means extending through said tubular inserts for locking the same detachably assembled to said tool handgrip.

3. The improvement defined in claim 1 characterized in that the adjacent longitudinal faces of said tubular insert and of said metallic handgrip are shaped cornplementally to one another to nest together with their exterior opposite lateral edges merging smoothly and juxtaposed surfaces of said tubular insert and of said cut away portions of said handgrip being complementally shaped and interlocking to prevent relative movement therebetween.

4. In a handle structure for a pneumatically-actuated percussive tool of the type having a reciprocating impact delivering element, that improvement which comprises a pair of oppositely-directed rigid handgrips adapted to be secured at their midportion to the outer end of said percussive tool, the handgrip portions being cut away along the longitudinal side remote from the body of said tool and being full-bodied over their lower exterior surfaces, elongated hollow inserts shaped to replace the cut away portions of said handgrip and seated in each of said cut-away portions and cooperating therewith in forming generally circular handgrips, means closing the opposite ends of said hollow inserts to preclude the entry of foreign matter, said inserts being of resilient shock-absorbent material and so positioned as to receive the pressure applied by the operator to said handgrips to advance the tool into the material being worked by the percussive tool.

5. A handle structure as defined in claim 4 characterized in that said inserts have the opposite ends thereof seated in retaining sockets at the opposite ends of the associated one of said handgrips.

6. A handle structure as defined in claim 5 characterized in the provision of retainer pin means extending lengthwise through said cut away portions of said handgrips and interiorly of each insert for releasably locking said inserts assembled to the rigid portions of said handgrips.

7. A handle structure as defined in claim 4 characterized in that said inserts are generally tubular and formed of an elastomeric material having a Shore softness in the vicinity of 30.

8. A handle structure as defined in claim 7 characterized in that said inserts are formed essentially of neoprene.

References Cited in the file of this patent UNITED STATES PATENTS 2,101,869 Noble Dec. 14, 1937 2,400,207 OFarrell et al. May 14, 1946 2,425,245 Johnson Aug. 5, 1947 2,831,463 Ekstrom et al. Apr. 22, 1958 

